Method for determining transmission mode in sidelink, terminal apparatus, and network apparatus

ABSTRACT

The present disclosure relates to a method for determining a transmission mode of a sidelink, a terminal apparatus, and a network apparatus. The method includes: a first terminal apparatus determining a first transmission mode from multiple transmission modes; and the first terminal apparatus performing, by adopting the first transmission mode, sidelink communications with other terminal apparatuses. The method for determining a transmission mode of a sidelink, the terminal apparatus, and the network apparatus in the present disclosure enable a terminal apparatus to adopt a suitable transmission mode for sidelink communications.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of InternationalPCT Application No. PCT/CN2018/112453, filed on Oct. 29, 2018, theentire content of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to the communication field, in particularto a method for determining a transmission mode in a sidelink, aterminal device and a network device.

BACKGROUND

A Vehicle-to-Everything system is a sidelink (SL) transmissiontechnology based on Long Term Evolution (LTE) device-to-device (D2D)communication. Different from a mode in a conventional LTE system inwhich communication data is received or sent by using a base station,the vehicle networking system adopts a mode of Device-to-Device directcommunication, and therefore the system has higher spectrum efficiencyand lower transmission latency.

In a New Radio (NR) vehicle to everything (V2X) system, multipletransmission modes are introduced, for example, transmission resourcesmay be allocated to a terminal device through a network device; or, theterminal device autonomously selects resources from a pre-configured ornetwork-configured resource pool, wherein the autonomously selectedresources may be selected randomly or by sensing; or, the terminaldevice may further assist other terminal devices in selecting resources,for example, a first terminal device sends auxiliary information to asecond terminal device, the auxiliary information includes availabletime-frequency resource information, channel measurement information andchannel quality information, so that the second terminal device selectstransmission resources based on the auxiliary information.

For the multiple transmission modes introduced in the NR-V2X system, howto determine a terminal device's own transmission mode is a problem tobe solved.

SUMMARY

Implementations of the present disclosure provide a method fordetermining a transmission mode in a sidelink, a terminal device and anetwork device, which can realize that the terminal device adopts anappropriate transmission mode for a sidelink communication.

In a first aspect, a method for determining a transmission mode in asidelink is provided, including: determining, by a first terminaldevice, a first transmission mode in multiple transmission modes; andadopting, by the first terminal device, the first transmission mode toperform a sidelink communication with another terminal device.

In a second aspect, a method for determining a transmission mode in asidelink is provided, including: receiving, by a first terminal device,a first message, wherein the first message includes first information,and the first information includes at least one piece of the followinginformation: a transmission mode adopted by the first terminal devicefor performing a sidelink communication, a group identifier of aterminal device group where the first terminal device is located, andgroup head information of the terminal device group, wherein the grouphead information is used for indicating a group head in the terminaldevice group, and the group head is a terminal device with a resourcecoordination or allocation function in the terminal device group;determining a first transmission mode in multiple transmission modesaccording to the first message; and sending first configurationinformation to the first terminal device, wherein the firstconfiguration information is used for indicating the first terminaldevice to adopt the first transmission mode to perform the sidelinkcommunication with another terminal device.

In a third aspect, a terminal device is provided. The terminal deviceincludes units for implementing the method in the first aspect orvarious implementations thereof. Specifically, the terminal deviceincludes function modules for performing the method in the above firstaspect or various implementations thereof.

In a fourth aspect, a network device is provided. The network deviceincludes units for performing the method in the second aspect or variousimplementations thereof. Specifically, the network device includesfunctional modules for performing the method in the above second aspector various implementations thereof.

In a fifth aspect, a terminal device is provided. The terminal deviceincludes a processor and a memory. The memory is configured to store acomputer program, and the processor is configured to call and run thecomputer program stored in the memory to execute the method in the firstaspect or various implementations thereof.

In a sixth aspect, a network device is provided. The network deviceincludes a processor and a memory. The memory is configured to store acomputer program, and the processor is configured to call and run thecomputer program stored in the memory to execute the method in thesecond aspect or various implementations thereof.

In a seventh aspect, a chip is provided for implementing the method inany one of above first to second aspects or the method in variousimplementations thereof. Specifically, the chip includes a processorconfigured to call and run a computer program from a memory and a devicehaving the chip installed therein executes the method in any one of theabove first to second aspects or in various implementations thereof.

In an eighth aspect, a computer-readable storage medium is provided forstoring a computer program that enables a computer to execute the methodin any one of the above first to second aspects or variousimplementations thereof.

In a ninth aspect, a computer program product is provided, includingcomputer program instructions that enable a computer to execute themethod in any one of the above first to second aspects or variousimplementations thereof.

In a tenth aspect, a computer program is provided which, when being runon a computer, enables a computer to execute the method in any one ofthe above first to second aspects or various implementations thereof.

According to the above technical solutions, a network device or terminaldevice configures transmission modes for one or more terminal deviceswhen performing a sidelink, especially for multiple terminal device in aunicast or multicast communication, an appropriate transmission mode maybe configured according to actual applications, thereby avoidingresource conflicts and improving a resource utilization rate and a datatransmission efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an architecture of a communicationsystem according to an implementation of the present disclosure.

FIG. 2 is a schematic diagram of a sidelink system according to animplementation of the present disclosure.

FIG. 3 is a schematic diagram of a method for determining a transmissionmode in a sidelink according to an implementation of the presentdisclosure.

FIG. 4 is another schematic diagram of a method for determining atransmission mode in a sidelink according to an implementation of thepresent disclosure.

FIG. 5 is a schematic block diagram of a terminal device according to animplementation of the present disclosure.

FIG. 6 is a schematic block diagram of a network device according to animplementation of the present disclosure.

FIG. 7 is a schematic block diagram of a communication system accordingto an implementation of the present disclosure.

FIG. 8 is a schematic block diagram of a communication system accordingto an implementation of the present disclosure.

FIG. 9 is a schematic block diagram of a communication system providedby an implementation of the present disclosure.

DETAILED DESCRIPTION

The technical solution in implementations of the present disclosure willbe described below with reference to the drawings in implementations ofthe present disclosure. It is apparent that the implementationsdescribed are just some implementations of the present disclosure, butnot all implementations of the present disclosure. According to theimplementations of the present disclosure, all other implementationsachieved by a person of ordinary skill in the art without paying aninventive effort shall fall within the protection scope of the presentdisclosure.

The technical solutions of the implementations of the present disclosuremay be applied to various communication systems, such as a Global Systemof Mobile communication (GSM) system, a Code Division Multiple Access(CDMA) system, a Wideband Code Division Multiple Access (WCDMA) system,a General Packet Radio Service (GPRS), a Long Term Evolution (LTE)system, a LTE Frequency Division Duplex (FDD) system, a LTE TimeDivision Duplex (TDD) system, a Universal Mobile TelecommunicationSystem (UMTS), a Worldwide Interoperability for Microwave Access (WiMAX)communication system, or a 5G system, etc.

Illustratively, a communication system 100 applied in an implementationof the present disclosure is shown in FIG. 1. The communication system100 may include a network device 110, and the network device 110 may bea device that communicates with a terminal device 120 (or referred to asa communication terminal, or a terminal). The network device 110 mayprovide communication coverage for a specific geographical area, and maycommunicate with terminal devices located within the coverage area.Optionally, the network device 110 may be a Base Transceiver Station(BTS) in a GSM system or CDMA system, a NodeB (NB) in a WCDMA system, anEvolutional Node B (eNB or eNodeB) in a LTE system, or a radiocontroller in a Cloud Radio Access Network (CRAN), or the network devicemay be a mobile switch center, a relay station, an access point, avehicle-mounted device, a wearable device, a hub, a switch, a bridge, arouter, or a network side device in a 5G network, or a network device ina future evolved Public Land Mobile Network (PLMN), etc.

The communication system 100 also includes at least one terminal device120 located within the coverage area of the network device 110. As usedherein, the term “terminal device” includes, but not limited to, adevice configured to connect via a wired circuit, for example, via aPublic Switched Telephone Network (PSTN), a Digital Subscriber Line(DSL), a digital cable, a direct cable; and/or another dataconnection/network; and/or via a wireless interface, for instance, for acellular network, a Wireless Local Area Network (WLAN), a digitaltelevision network such as a Digital Video Broadcasting-Handheld (DVB-H)network, a satellite network, and an AM-FM broadcast transmitter; and/oran apparatus, of another communication terminal, configured toreceive/send a communication signal; and/or an Internet of Things (IoT)device. A terminal device configured to communicate via a wirelessinterface may be referred to as a “wireless communication terminal”, a“wireless terminal” or a “mobile terminal”. Examples of the mobileterminal include, but not limited to, a satellite or cellular telephone,a Personal Communication System (PCS) terminal capable of combining witha cellular wireless telephone and data processing, faxing, and datacommunication capabilities, a Personal Digital Assistant (PDA) that mayinclude a radio telephone, a pager, an internet/intranet access, a Webbrowser, a memo pad, a calendar, and/or a Global Positioning System(GPS) receiver, and a conventional laptop and/or palmtop receiver oranother electronic apparatus including a radio telephone transceiver.Optionally, the terminal device may be referred to as an accessterminal, a User Equipment (UE), a subscriber unit, a subscriberstation, a mobile station, a mobile platform, a remote station, a remoteterminal, a mobile device, a user terminal, a terminal, a wirelesscommunication device, a user agent, or a user apparatus. The accessterminal may be a cellular phone, a cordless phone, a Session InitiationProtocol (SIP) phone, a Wireless Local Loop (WLL) station, a PersonalDigital Assistant (PDA), a handheld device with a wireless communicationfunction, a computing device, or another processing device connected toa wireless modem, a vehicle-mounted device, a wearable device, aterminal device in a 5G network, or a terminal device in a futureevolved Public Land Mobile Network (PLMN), or the like.

Optionally, Device to Device (D2D) communication may be performedbetween the terminal devices 120.

Optionally, the 5G system or 5G network may be referred to as a NewRadio (NR) system or a NR network.

FIG. 1 shows one network device and two terminal devices as an example.Optionally, the wireless communication system 100 may include multiplenetwork devices, and other quantity of terminal devices may be includedwithin coverage area of each network device, and the implementations ofthe present disclosure are not limited thereto.

Optionally, the communication system 100 may include other networkentities such as a network controller, and a mobile management entity,and the implementations of the present disclosure are not limitedthereto.

It should be understood that, a device with a communication function ina network/system in the implementation of the present disclosure may bereferred to as a communication device. The communication system 100shown in FIG. 1 is taken as an example, the communication device mayinclude a network device 110 and terminal devices 120 which havecommunication functions, and the network device 110 and the terminaldevices 120 may be the specific devices described above, which will notbe described here again. The communication device may further includeother devices in the communication system 100, such as networkcontrollers, mobile management entities, and other network entities, andthe implementations of the present disclosure are not limited thereto.

It should be understood that the terms “system” and “network” are oftenused interchangeably in this specification. The term “and/or” usedherein is merely an association relation describing associated objects,indicating that there may be three relations, for example, A and/or Bmay indicate three cases: A alone, A and B, and B alone. In addition,the symbol “/” herein generally indicates that objects before and afterthe symbol “/” have an “or” relation.

In Release 14 (Rel-14) of the 3rd generation partnership project (3GPP),the V2X technology is standardized, and two transmission modes aredefined: mode 3 and mode 4, wherein FIG. 2 shows a schematic diagram oftwo transmission modes in a V2X system according to an implementation ofthe present disclosure.

As shown in FIG. 2, mode 3 on the left indicates that transmissionresources of a vehicle terminal are allocated by a base station througha downlink (DL), and the vehicle terminal transmits data on the sidelinkaccording to the resources allocated by the base station; the basestation may allocate to the terminal a resource for a singletransmission or a resource for a semi-static transmission.

As shown in FIG. 2, mode 4 on the right indicates that a vehicleterminal adopts a transmission mode of sensing plus reservation. Thevehicle terminal acquires a set of available transmission resources in aresource pool by sensing, and the terminal randomly selects a resourcefrom the set for data transmission. Since services in the V2X have aperiodic feature, the terminal usually adopts a semi-static transmissionmode, that is, after selecting a transmission resource, the terminalwill continuously use the resource in multiple transmission periods,thus reducing probabilities of resource re-selection and resourceconflict. The terminal will carry information of a resource reserved fornext transmission in the control information of a current transmission,so that other terminals can determine whether the resource is reservedand used by the user by detecting the control information of the user,thus achieving a purpose of reducing resource conflicts.

In the NR-V2X system, similar to the above, multiple transmission modesare introduced, for example, mode 1 and mode 2 may be included, whereinmode 1 is that a network device allocates transmission resources for theterminal, which is similar to mode 3 in LTE-V2X, and the terminal deviceadopts the transmission resources allocated by the network device;however, in mode 2, the terminal device selects the transmissionresources, and mode 2 is divided into several sub-modes, for example,the following modes may be specifically included.

1. Mode 2a: a terminal device selects transmission resourcesindependently, which is similar to the mode 4 in the LTE-V2X mentionedabove. For example, the terminal selects resources independently from apre-configured or network-configured resource pool, and may selectresources randomly or by sensing.

2. Mode 2b: a terminal assists other terminals in selecting resources;for example, a first terminal sends auxiliary information to a secondterminal, and a terminal device receiving the auxiliary information maydetermine transmission resources according to the auxiliary information,wherein the auxiliary information may include one or more of thefollowing information: available time-frequency resource information,available transmission resource set information, channel measurementinformation and channel quality information, such as Channel StateInformation (CSI), Channel Quality Indicator (CQI), Precoding MatrixIndicator (PMI), rank indication (RI), Reference Signal Receiving Power(RSRP), Reference Signal Receiving Quality (RSRQ), Received SignalStrength Indicator (RSSI), interference information and path lossinformation.

3. Mode 2c: a terminal device selects resources from transmissionresources configured for it. For example, a network device may configuretransmission resources for each terminal in a group of terminal devices,wherein the transmission resource for each terminal device may be sameor different. When any terminal has a sidelink data transmission, thetransmission resource configured by a network device may be used fordata transmission. For example, when the network device configures thesame resources for each terminal device in a group of terminal devices,the terminal device that needs to perform the sidelink data transmissionmay select available resources from the configured resources by mannerssuch as sensing; or, the network device may configure differenttransmission resources for each terminal device in a group of terminaldevices, and the terminal device that needs to perform the sidelink datatransmission may select available resources from the resourcesconfigured therefor.

Mode 2d: a first terminal device allocates transmission resources for asecond terminal device. For example, for multiple terminal devices in amulticast link, if the first terminal device is a group head in themulticast link and the second terminal device is a group member of thegroup, the first terminal device may directly allocate time-frequencyresources for the second terminal device for a downlink transmission.

For multiple transmission modes in the NR V2X, how one terminaldetermines its own transmission mode is a problem that needs to besolved.

In mode 2b or mode 2d, the terminal device is usually in a certainunicast or multicast link, and other terminal device (such as a grouphead in group communication or an opposite terminal device in unicastcommunication) allocates transmission resources for the terminal device,or other terminal sends auxiliary information which is used for theterminal device to select resources. In other transmission modes, theterminal device mainly relies on the transmission resources allocated bythe network device for performing the sidelink communication.

Specifically, if the terminal device is outside cell coverage and doesnot perform unicast or multicast communication with other terminaldevices, the terminal device only performs broadcast communication, andthe terminal device can work in the above mode 2a. When the terminaldevice and other terminal device form a unicast link or a multicastlink, they can perform unicast communication or multicast communicationwith other terminal devices. At this time, the terminal device mayfurther work in mode2b or mode2d.

For any terminal device, if the terminal device is currently working inmode 1, but the terminal device performs unicast communication ormulticast communication at the same time, other terminal device ofunicast communication or multicast communication may also adopt mode 1,that is, all transmission resources of the unicast communication and themulticast communication are determined by the network device. However,if each group member in multicast communication are not in same one celland there is no resource coordination between cells, then the networkdevice of each group member may cause transmission resource conflictswhen allocating transmission resources to the respective group members,that is, the transmission resources of terminal devices in differentcells conflict with each other. At this time, the terminal devices mayadopt mode 2b or mode 2d, for example, the group head allocatestransmission resources to each group member, thus avoiding transmissioninterference among users in the group. Then, the group members need tosend the information of the unicast link or multicast link where theyare currently located to the group head or the network device, and thenetwork decides the transmission mode of the terminal device, or thenetwork device decides whether the terminal device needs to switchmodes, so as to avoid conflicts. Therefore, an implementation of thepresent disclosure provides a method for determining a transmission modein a sidelink, so that the terminal device may switch a transmissionmode, thus being able to deal with various scenarios and avoidingresource conflicts.

FIG. 3 shows a schematic flow chart of a method 200 for determining atransmission mode in a sidelink according to an implementation of thepresent disclosure, the method 200 may be performed by any terminaldevice, which is called a first terminal device here. Specifically, thefirst terminal device may perform a sidelink communication with anotherterminal device, for example, the first terminal device may be anyterminal device shown in FIG. 1 or FIG. 2. As shown in FIG. 3, themethod 200 includes S210-S220. In S210, the first terminal devicedetermines a first transmission mode in multiple transmission modes; inS220, the first terminal device adopts the first transmission mode toperform a sidelink communication with another terminal device.

Specifically, in S210, the first terminal device may determine the firsttransmission mode in the multiple transmission modes through multipleways. For example, the first terminal device determines the firsttransmission mode through configuration of a network device, that is,the first terminal device receives configuration information sent by thenetwork device, wherein the configuration information indicates thefirst transmission mode, and the first terminal device determines thefirst transmission mode in the multiple transmission modes according tothe first configuration information, or, the first terminal device mayfurther determine the first transmission mode in the multipletransmission modes according to its own related messages or withreference to information of another terminal device; or, the firstterminal device may further receive configuration information sent byanother terminal device, wherein the configuration information is usedfor indicating the first transmission mode, so that the first terminaldevice may determine the first transmission mode in the multipletransmission modes according to the configuration information.Implementations of the present disclosure are not limited to this.

In S220, the first terminal device adopts the first transmission modedetermined in S210 to perform the sidelink communication with anotherterminal device. In the above, before determining the first transmissionmode in S210, the first terminal device may adopt a second transmissionmode to perform the sidelink communication with another terminal device.After determining the first transmission mode, the first terminal deviceupdates the transmission mode used for the sidelink communication fromthe second transmission mode to the first transmission mode.

It should be understood that the second transmission mode may be same asor different from the first transmission mode. If the first transmissionmode is same as the second transmission mode, the first terminal devicedoes not change the transmission mode in S220. If the first transmissionmode is different from the second transmission mode, the first terminaldevice changes the transmission mode from the second transmission modeto the first transmission mode in S220.

It should be understood that the first transmission mode or the secondtransmission mode may be any type of transmission mode, for example, theabove-mentioned mode 1, or any one of the modes 2a-2d in the mode 2, andimplementations of the present disclosure are not limited to this.

The method 200 for determining the transmission mode in the sidelinkaccording to an implementation of the present disclosure will bedescribed in detail with reference to different implementations.

Implementation one: the first terminal device is configured through thenetwork device to adopt the first transmission mode.

Specifically, the first terminal device receives the first configurationinformation sent by the network device, wherein the first configurationinformation is used for indicating the first transmission mode, thefirst terminal device determines the first transmission mode in multipletransmission modes according to the first configuration information, andadopts the first transmission mode to perform the sidelink communicationwith other terminal devices.

Optionally, the first configuration information sent by the networkdevice received by the first terminal device may be carried in, forexample, broadcast information, Radio Resource Control (RRC) signalingor downlink control information, and implementations of the presentdisclosure are not limited to this.

Optionally, the first configuration information may further include atleast one piece of the following information: group identificationinformation of a terminal device group where the first terminal deviceis located, type information of multicast communication or broadcastcommunication, Radio Access Technology (RAT) class indicationinformation, and Quality of Service (QoS) attribute information.

Since the first terminal device may have one or more groups of multicastcommunications at the same time or have a unicast communication and amulticast communication at the same time, the first configurationinformation sent by the network device to the first terminal device mayinclude not only the first transmission mode, but also the groupidentification information of the terminal device group where the firstterminal device is located, so that the first terminal device maydetermine which terminal device group adopts the first transmission modeto perform the sidelink communication, wherein the first terminal devicemay adopt the same or different transmission modes in different terminaldevice groups.

Optionally, the first configuration information may further include thetypes of unicast communication, multicast communication or broadcastcommunication, that is, the first configuration information sent by thenetwork device to the first terminal device indicates that the firstterminal device adopts the first transmission mode to perform thesidelink communication during the unicast communication, multicastcommunication or broadcast communication. For example, if the typeinformation indicated by the first configuration information is themulticast communication, then it may be specifically determined whichmulticast link adopts the first transmission mode to perform thesidelink communication with reference to the identification informationof the terminal device group included in the first configurationinformation. For another example, if the type indicated by the firstconfiguration information is the broadcast communication, the firstterminal device may adopt the first transmission mode to perform thesidelink communication with other terminal devices when determining thebroadcast communication.

Optionally, the first configuration information may further include RATclass indication information, for example, if the RAT class indicationinformation may be used for indicating LTE or NR, then the firstterminal device determines to adopt the first transmission mode toperform the sidelink communication in the LTE system or NR systemaccording to the first configuration information, wherein the firstterminal device may adopt the same or different transmission modes toperform the sidelink communication in the LTE system and NR system.

Optionally, the first configuration information may further include QoSattribute information, for example, the QoS attribute information may beused for indicating QoS levels, wherein different levels may correspondto the same or different transmission modes, so that the first terminaldevice may determine the transmission mode under a certain QoS level asthe first transmission mode.

It should be understood that the method 200 may further include: thefirst terminal device sends a first message to the network device.Specifically, the first message may be sent before the network devicesends the first configuration information, so that the network devicemay determine the first transmission mode according to the firstmessage, or, the first message may be sent after the network devicesends the first configuration information, so that the network devicemay re-determine the transmission mode according to the first message,so that the first terminal device may update the current firsttransmission mode. For convenience of explanation, taking a case inwhich the first terminal device sends the first message to the networkdevice before the network device sends the first configurationinformation as an example, the first message is used for the networkdevice to determine the first transmission mode. It should be understoodthat the first message sent by the first terminal device to the networkdevice may be carried in, for example, uplink control information, MediaAccess Control Control Element (MAC CE) or RRC signaling, andimplementations of the present disclosure are not limited to this.

In the above, the first message may include related information of thefirst terminal device, for example, the first message may include firstinformation, wherein the first information includes at least one pieceof the following information: the transmission mode adopted by the firstterminal device for performing the sidelink communication, groupidentifier of the terminal device group where the first terminal deviceis located, and group head information of the terminal device group.

It should be understood that the transmission mode adopted by the firstterminal device for performing the sidelink communication included inthe first information refers to the transmission mode adopted whensending the first information. For example, if the first information issent before the network device configures the first transmission mode,the transmission mode indicated in the first information is atransmission mode currently used by the first terminal device, which maybe the first transmission mode or other transmission modes, if the firstinformation is sent after the network device configures the firsttransmission mode, the transmission mode indicated in the firstinformation is a transmission mode currently used by the first terminaldevice, that is, the first transmission mode.

Optionally, the transmission mode adopted by the first terminal devicefor performing the sidelink communication included in the firstinformation is the transmission mode adopted by the first terminaldevice in the terminal device group. The same terminal device may adoptsame or different transmission modes when it is located in differentterminal device groups. Therefore, the transmission mode adopted by theterminal device for performing the sidelink communication described inan implementation of the present disclosure is the transmission modeadopted by the terminal device in its own terminal device group. Forexample, the network device may configure, for the first terminaldevice, a transmission mode for performing the sidelink communication ina certain terminal device group.

It should be understood that the group head information in the firstinformation may be used for indicating the group head in the terminaldevice group, wherein the group head is a terminal device with resourcecoordination, control, management or allocation function in the terminaldevice group. For example, if the first terminal device is not the grouphead in the terminal device group, the group head information mayinclude identification information of the group head in the terminaldevice group; or, if the first terminal device is the group head in theterminal device group, the group head information may be used forindicating that the first terminal device is the group head in theterminal device group, or the group head information may further includeidentification information of the group head in the terminal devicegroup where the first terminal device is located, and the network devicedetermines that the group head is the first terminal device.

It should be understood that the terminal device group in animplementation of the present disclosure refers to the unicast ormulticast link where the first terminal device is located, or if thefirst terminal device does not belong to any unicast or multicast link,for example, the first terminal device performs a broadcastcommunication, the terminal device group may only include the firstterminal device. For example, the terminal device group may include twoterminal devices, and the two terminal devices form a unicast link andperform unicast communication; or, the terminal device group may furtherinclude more than two terminal devices, and the multiple terminaldevices form a multicast link and perform multicast communication, andimplementations of the present disclosure are not limited to this. Forconvenience of description and conciseness, both unicast link andmulticast link are referred to as terminal device groups in the presentdisclosure, which will not be described again.

Optionally, when the terminal device group includes more than twoterminal devices, the group identifier of the terminal device group isidentification information for identifying the terminal device group;when the terminal device group includes two terminal devices, the groupidentifier of the terminal device group may be the identificationinformation for identifying the terminal device group, or the groupidentifier of the terminal device group may be identificationinformation of the other terminal device except the first terminaldevice.

Optionally, the network device may receive first information sent by thefirst terminal device, wherein the first information is relatedinformation of the first terminal device, and the network device mayfurther receive messages sent by another terminal device, for example,the network device may further receive second information sent by asecond terminal device, and the second terminal device may be anotherterminal device except the first terminal device, for example, thesecond terminal device may be any terminal device belonging to the sameterminal device group as the first terminal device, and the secondinformation may include related information of the second terminaldevice, for example, the second information may include identificationinformation of the second terminal device, transmission mode adopted bythe second terminal device for performing a sidelink communication andfirst indication information, wherein the first indication informationis used for indicating cell information or coverage informationcorresponding to the second terminal device. Therefore, the networkdevice may receive information of one or more terminal devices, andimplementations of the present disclosure are not limited to this.

Optionally, the network device receives the first message sent by thefirst terminal device, and the first message may further include relatedinformation of one or more other terminal devices, that is, the networkdevice receives the related information of other terminal devicesthrough the first terminal device. For example, if the first terminaldevice is the group head in the terminal device group, the firstterminal device may send the information of other terminal devices inthe terminal device group to the network device. Specifically, takingthe first terminal device sending related information of any terminaldevice as an example, the first message may include second information,wherein the second information may include at least one piece of thefollowing information: identification information of the second terminaldevice, transmission mode adopted by the second terminal device forperforming the sidelink communication, and the first indicationinformation, wherein the second terminal device is a terminal deviceother than the first terminal device, for example, the second terminaldevice may be any terminal device belonging to the same terminal devicegroup as the first terminal device, and the first indication informationis used for indicating the cell information or coverage informationcorresponding to the second terminal device.

It should be understood that the method 200 may further include: thefirst terminal device receives the second information sent by the secondterminal device, so that the first terminal device sends the secondinformation to the network device. Optionally, the second informationsent by the second terminal device to the first terminal device may becarried in a sidelink transmission channel, for example, the sidelinktransmission channel may be a Physical Sidelink Control Channel (PSCCH)or a Physical Sidelink Shared Control Channel (PSSCH).

The above-mentioned first indication information may be used forindicating cell information or coverage information corresponding to thesecond terminal device. For example, if the second terminal device islocated outside the cell coverage area, the first indication informationis used for indicating that the second terminal device is locatedoutside the cell coverage area.

For another example, if the second terminal device is located within thecell coverage area, the first indication information includes the cellidentification information of the cell where the second terminal deviceis located, so that the network device may determine the cell where thesecond terminal device is located.

For another example, if the second terminal device is located outsidethe coverage area of the cell where the first terminal device islocated, the first indication information is used for indicating thatthe second terminal device is located outside the coverage area of thecell where the first terminal device is located and/or the firstindication information includes cell identification information of thecell where the second terminal device is located. Specifically, if thesecond terminal device is located outside the cell coverage area, thatis, outside the coverage area of the cell where the first terminal islocated, the first indication information may be used for indicatingthat the second terminal device is located outside the coverage area ofthe cell where the first terminal device is located or outside the cellcoverage area. If the second terminal device is located within the cellcoverage area but outside the coverage area of the cell where the firstterminal is located, the first indication information may be used forindicating that the second terminal device is located outside thecoverage area of the cell where the first terminal device is located, orthe first indication information may further include the cellidentification information of the cell where the second terminal deviceis located, so that the network device may determine the cell where thesecond terminal device is located.

For another example, if the second terminal device is located within thecoverage area of the cell where the first terminal device is located,the first indication information is used for indicating that the secondterminal device is located in the cell where the first terminal deviceis located, or, the first indication may further include the cellidentification information of the cell where the second terminal deviceis located, so that the network device may determine the cell where thesecond terminal device is located.

Optionally, the cell identification information may be one piece of thefollowing information: cell identifier (cell-ID), carrier frequencyinformation of the cell, carrier information of the cell, and Publicland mobile network (PLMN) information.

It should be understood that the network device determines thetransmission modes of all or part of the one or more terminal devicesaccording to the received related information of the one or moreterminal devices. Specifically, taking the above first terminal deviceand the second terminal device as an example, the network devicereceives the related information of the two terminal devices, forexample, the network device may receive the first information and thesecond information, and according to the first information and thesecond information, transmission modes may be configured for the firstterminal device and/or the second terminal device. Here, assuming thatthe network device has configured transmission modes for both the firstterminal device and the second terminal device, the network device maysend first configuration information to the first terminal device,wherein the first configuration information is used for indicating thefirst terminal device to adopt the first transmission mode to performthe sidelink communication. At the same time, the network device mayfurther send second configuration information to the second terminaldevice, wherein the second configuration information is used forindicating that the second terminal device also adopts the firsttransmission mode to perform the sidelink communication, or may alsoindicate that the second terminal device to adopt other transmissionmodes to perform the sidelink communication.

Or, the network device has configured the transmission modes for boththe first terminal device and the second terminal device, and thenetwork device may send first configuration information to the firstterminal device, wherein the first configuration information is used forindicating the first terminal device to adopt the first transmissionmode to perform the sidelink communication. At the same time, thenetwork device may further indicate the transmission mode of the secondterminal device through the first configuration information, so that thefirst terminal device may send second configuration information to thesecond terminal device according to the first configuration information,and the second configuration information is used for indicating thetransmission mode assigned by the network device to the second terminaldevice, for example, the second configuration information may indicatethe second terminal device to adopt the first transmission mode toperform the sidelink communication or the second configurationinformation may also indicate the second terminal device to adopt othertransmission modes to perform the sidelink communication.

It should be understood that various conditions and factors may be takeninto consideration when the network device configures the transmissionmode for the terminal device by the network device, and resourceconflicts are to be avoided as much as possible according to actualapplications. For example, here, taking the network device configuringthe transmission mode for the terminal device group where the firstterminal device is located as an example, if each terminal device in theterminal device group is located in the same cell, the network devicemay configure all terminal devices in the terminal device group toacquire resources of the sidelink by using the above-mentioned mode 1,or also by using the above-mentioned mode 2c or other modes. However, ifthe terminal devices in the terminal device group are located indifferent cells, and if the terminal devices in the terminal devicegroup are still configured to acquire resources in the mode 1, becausethere is no resource coordination between cells, the network devicecorresponding to each group member may cause transmission resourceconflicts when allocating transmission resources to the group members.Therefore, the network device may configure the terminal devices in theterminal device group to adopt mode 2b or mode 2d, and a group head mayallocate transmission resources to each group member, thus avoidingtransmission interference among users in the group. For another example,if the first terminal device is located outside the cell coverage area,and there is no other terminal device in the terminal device group, thatis, the first terminal device does not perform unicast or multicastcommunication with other terminal devices, the network device mayconfigure the first terminal device to acquire the sidelink resources byusing mode 2a.

Therefore, the network device acquires the related information of one ormore terminal devices, configures the transmission mode for the one ormore terminal devices according to the information, and determines anappropriate transmission mode adopted by a terminal device to performthe sidelink communication according to the cell information ofdifferent terminal devices or the information of the terminal devicegroup, so as to improve a resource utilization rate and datatransmission efficiency.

Implementation two: the first terminal device selects a firsttransmission mode in multiple transmission modes.

Specifically, the first terminal device determines the firsttransmission mode in the multiple transmission modes according to asecond message, and adopts the first transmission mode to perform thesidelink communication with other terminal devices. In the above, thesecond message may include related information of the first terminaldevice, for example, the second message may include third information,wherein the third information includes the transmission mode adopted bythe first terminal device for performing the sidelink communicationand/or a group identifier of the terminal device group.

It should be understood that the first terminal device determines thefirst transmission mode according to the second message, and the thirdinformation in the second message may include the transmission modecurrently adopted by the first terminal device for performing thesidelink communication. For example, if the transmission mode includedin the third information is the second transmission mode adopted by thefirst terminal device before determining the first transmission mode,the first terminal device may update the second transmission mode to thefirst transmission mode after determining the first transmission modeaccording to the second message, wherein the first transmission mode andthe second transmission mode may be the same or different. For anotherexample, if the transmission mode included in the third information is atransmission mode adopted by the first terminal device after determiningthe first transmission mode, that is, if the third information includesthe first transmission mode, the first terminal device may determine thetransmission mode to be adopted at the next moment according to thesecond message and update the first transmission mode currently used,where the first transmission mode and the updated transmission mode maybe the same or different. For convenience of explanation, here, take thetransmission mode included in the third information as the transmissionmode adopted by the first terminal device before determining the firsttransmission mode as an example.

Optionally, the transmission mode currently adopted by the firstterminal device for performing the sidelink communication included inthe third information is the transmission mode adopted by the firstterminal device in the terminal device group.

Optionally, the third information included in the second message is therelated information of the first terminal device, and may furtherinclude other information, for example, the third information mayfurther include group head information of the terminal device groupwhere the first terminal device is located. The group head informationmay be used for indicating the group head in the terminal device group,wherein the group head is a terminal device with resource coordination,control, management or allocation function in the terminal device group.For example, if the first terminal device is not the group head in theterminal device group, the group head information may includeidentification information of the group head in the terminal devicegroup; or, if the first terminal device is a group head in the terminaldevice group, the group head information may be used for indicating thatthe first terminal device is the group head in the terminal devicegroup.

It should be understood that, similar to the concept of the terminaldevice group in Implementation one, the terminal device group in thisimplementation may further refer to the unicast link or multicast linkwhere the first terminal device is located, or only include the firstterminal device, and will not be described in detail here.

Optionally, for the terminal device group where the first terminaldevice is located, if the terminal device group only includes the firstterminal device, that is, the first terminal device does not performunicast or multicast communication with other terminal device, theterminal device may determine to adopting the above mode 1 to acquiresidelink resources, or if at the same time the first terminal device isalso located outside the cell coverage area, the terminal device mayalso determine to adopt the mode 2a mode to acquire the sidelinkresources, but implementations of the present disclosure are not limitedto this.

Optionally, for the terminal device group where the first terminaldevice is located, if the terminal device group includes multipleterminal devices, the first terminal device may further determine thefirst transmission mode with reference to related information of anotherterminal device. For example, the first terminal device may be the grouphead in the terminal device group, wherein the group head may determinethe transmission mode adopted by the group head according to the relatedinformation of group members, or may further determine the transmissionmodes adopted by other group members.

Here, taking the terminal device group including multiple terminaldevices as an example, the first terminal device is any terminal devicein the terminal device group, and a third terminal device is another onearbitrary terminal device. The first terminal device may determine thefirst transmission mode with reference to the related information of thethird terminal device. Specifically, the second message may furtherinclude fourth information, wherein the fourth information includes atleast one piece of the following information: identification informationof the third terminal device, transmission mode adopted by the thirdterminal device for performing the sidelink communication, and secondindication information, wherein the third terminal device is a terminaldevice other than the first terminal device. For example, the thirdterminal device may be any other terminal device in the same terminaldevice group as the first terminal device, wherein the first terminaldevice may be the group head and the third terminal device is any groupmember in the terminal device group.

Optionally, the method 200 may further include: the first terminaldevice receives fourth information sent by the third terminal device,wherein the fourth information may be carried in a sidelink transmissionchannel, for example, the sidelink transmission channel may be PSCCH orPSSCH.

The second indication information may be used for indicating cellinformation or coverage information corresponding to the third terminaldevice. For example, if the third terminal device is located outside thecell coverage area, the second indication information is used forindicating that the third terminal device is located outside the cellcoverage area.

For another example, if the third terminal device is located within thecell coverage area, the second indication information includes the cellidentification information of the cell where the third terminal deviceis located.

Alternatively, for another example, if the third terminal device islocated outside the coverage area of the cell where the first terminaldevice is located, the second indication information is used forindicating that the third terminal device is located outside thecoverage area of the cell where the first terminal device is locatedand/or the second indication information includes cell identificationinformation of the cell where the third terminal device is located.Specifically, if the third terminal device is located outside the cellcoverage area, that is the third terminal device is located outside thecoverage area of the cell where the first terminal device is located,the first indication information may be used for indicating that thethird terminal device is located outside the coverage area of the cellwhere the first terminal device is located or outside the cell coveragearea. If the third terminal device is located within the cell coveragearea but outside the coverage area of the cell where the first terminaldevice is located, the first indication information may be used forindicating that the third terminal device is located outside thecoverage area of the cell where the first terminal device is located, orthe first indication information may further include the cellidentification information of the cell where the third terminal deviceis located, so that the first terminal device may determine the cellwhere the third terminal device is located.

For another example, if the third terminal device is located inside thecoverage area of the cell where the first terminal device is located,the second indication information is used for indicating that the thirdterminal device is located in the cell where the first terminal deviceis located, or, the first indication may further include the cellidentification information of the cell where the third terminal deviceis located, so that the first terminal device may determine the cellwhere the third terminal device is located.

It should be understood that the first terminal device may considervarious conditions and factors to determine the first transmission modeby combining information of multiple terminal devices, and avoidresource conflicts as much as possible according to actual applications.In addition, the first terminal device may further configuretransmission modes for other terminal devices while determining to adoptthe first transmission mode. For example, if the first terminal deviceis the group head in the terminal device group, the first terminaldevice may further configure transmission modes of other terminaldevices.

For example, if each terminal device in the terminal device group wherethe first terminal device is located is located in the same cell, thefirst terminal device may configure all terminal devices in the terminaldevice group to adopt the above mode 1, or adopt the above Mode 2c orother modes to acquire the resources of the sidelink. However, if theterminal devices in the terminal device group are located in differentcells, and if the terminal devices in the terminal device group arestill configured to adopt the mode 1 to acquire resources, because thereis no resource coordination between cells, the network devicecorresponding to each group member may cause transmission resourceconflicts when allocating transmission resources to the group members.Therefore, the first terminal device may configure the terminal devicesin the terminal device group to adopt mode 2b or mode 2d, and the grouphead may allocate transmission resources to each group member, thusavoiding the transmission interference between users in the group.

It should be understood that if the first terminal device configurestransmission modes for other terminal devices, the method 200 mayfurther include: the first terminal device sends third configurationinformation to the third terminal device, wherein the thirdconfiguration information is used for indicating the transmission modeadopted by the third terminal device for performing the sidelinkcommunication. For example, if the first terminal device may configurethe third terminal device to adopt the first transmission mode as well,the third configuration information is used for indicating the thirdterminal device to adopt the first transmission mode to perform thesidelink communication; or, the first terminal device may furtherconfigure other transmission modes for the third terminal device, andimplementations of the present disclosure are not limited to this.

Implementation three: the first terminal device is configured throughanother terminal device to adopt the first transmission mode.

Specifically, it can be seen from the combination of the firstimplementation and the second implementation above that the firstterminal device is any terminal device, and the first terminal devicemay further receive a transmission mode sent by another terminal device.For example, the first terminal device receives fourth configurationinformation sent by a fourth terminal device, wherein the fourthconfiguration information is used for indicating the first transmissionmode, and the first transmission mode may be configured for the firstterminal device by the network device, and the first terminal isnotified by the fourth configuration information sent by the fourthterminal device; or, the first transmission mode is configured by thefourth terminal device for the first terminal device, and is notified tothe first terminal device through the fourth configuration information.The first terminal device determines the first transmission mode in themultiple transmission modes according to the fourth configurationinformation, and adopts the first transmission mode to perform thesidelink communication with another terminal device.

Combining the above implementations 1 and 2, the first terminal devicemay be any terminal device in the terminal device group where it islocated. For example, the first terminal device may be a terminal devicein the terminal device group except a group head, that is, a groupmember in the terminal device group, wherein the group head is aterminal device with resource coordination, management, control orallocation function in the terminal device group. The fourth terminaldevice is any another terminal device in the terminal device group, forexample, the fourth terminal device may be the group head or a groupmember in the terminal device group.

Optionally, the method 200 may further include that the first terminaldevice sends fifth information to the network device or the firstterminal device sends fifth information to the fourth terminal devicethen the fourth terminal device sends the fifth information to thenetwork device, so that the network device may determine that the firstterminal device adopts the first transmission mode according to thefifth information, or, the first terminal device sends the fifthinformation to the fourth terminal device, so that the fourth terminaldevice may determine that the first terminal device adopts the firsttransmission mode according to the fifth information, or, the firstterminal device may send the fifth information to the network device orthe fourth terminal device after determining the first transmission modeaccording to the fourth configuration information, and then the fifthinformation is used by the network device or the fourth terminal devicefor determining the transmission mode adopted by the first terminaldevice at the next moment.

Optionally, the fifth information sent by the first terminal device tothe network device may be carried in, for example, uplink controlinformation, MAC CE or RRC signaling, and implementations of the presentdisclosure are not limited to this.

Optionally, the fifth information sent by the first terminal device tothe fourth terminal device may be carried in a sidelink transmissionchannel, for example, the sidelink transmission channel may be PSCCH orPSSCH.

It should be understood that the fifth information is relatedinformation of the first terminal device, and the fifth information mayinclude at least one piece of the following information: thetransmission mode adopted by the first terminal device for performingthe sidelink communication, the group identifier of the terminal devicegroup, and third indication information.

Optionally, the transmission mode adopted by the first terminal devicefor performing the sidelink communication included in the fifthinformation refers to the transmission mode adopted when sending thefifth information. For example, if the fifth information is sent beforethe first terminal device receives the fourth configuration information,the transmission mode indicated in the fifth information is atransmission mode currently used by the first terminal device, which maybe the first transmission mode or other transmission modes. If the fifthinformation is sent after the first terminal device receives the fourthconfiguration information, the transmission mode indicated in the fifthinformation is a transmission mode currently used by the first terminaldevice, that is, the first transmission mode.

Optionally, the transmission mode adopted by the first terminal devicefor performing the sidelink communication included in the fifthinformation is the transmission mode adopted by the first terminaldevice in the terminal device group.

It should be understood that the group head information in the fifthinformation may be used for indicating the group head in the terminaldevice group, wherein the group head is the terminal device withresource coordination or allocation function in the terminal devicegroup. For example, if the first terminal device is not the group headin the terminal device group, the group head information may includeidentification information of the group head in the terminal devicegroup, or, if the first terminal device is the group head in theterminal device group, the group head information may be used forindicating that the first terminal device is the group head in theterminal device group, or the group head information may further includethe identification information of the group head in the terminal devicegroup where the first terminal device is located, and the network deviceor the fourth terminal device determines that the group head is thefirst terminal device.

It should be understood that, similar to Implementation one andImplementation two, the terminal device group in this implementationrefers to the unicast link or multicast link where the first terminaldevice is located, or if the first terminal device does not belong toany unicast or multicast link, the terminal device group may onlyinclude the first terminal device, which is not described in detailhere.

Optionally, the third indication information in the fifth information isused for indicating the cell information or coverage informationcorresponding to the first terminal device. For example, if the firstterminal device is located outside the cell coverage area, the thirdindication information is used for indicating that the first terminaldevice is located outside the cell coverage area.

For another example, if the first terminal device is located within thecell coverage area, the third indication information includes the cellidentification information of the cell where the first terminal deviceis located.

For another example, if the first terminal device is located outside thecoverage area of the cell where the fourth terminal device is located,the third indication information is used for indicating that the firstterminal device is located outside the coverage area of the cell wherethe fourth terminal device is located and/or the third indicationinformation includes cell identification information of the cell wherethe first terminal device is located.

For another example, if the first terminal device is located within thecoverage area of the cell where the fourth terminal device is located,the third indication information is used for indicating that the firstterminal device is located in the cell where the fourth terminal deviceis located.

It should be understood that the first terminal device receives thefourth configuration information sent by the fourth terminal device, andthe fourth configuration information is used for indicating the firstterminal device to adopt the first transmission mode to perform thesidelink transmission, and the first transmission mode may be configuredby the network device or the fourth terminal device. For the sake ofbrevity, the specific configuration process may refer to Implementationone and Implementation one, which will not be repeated here.

Therefore, in a method for determining a transmission mode in a sidelinkin an implementation of the present disclosure, a transmission modeadopted by one or more terminal devices when performing a sidelink isconfigured by a network device or a terminal device, especially formultiple terminal devices in unicast or multicast communication, theappropriate transmission mode may be configured according to actualapplications, thereby avoiding resource conflict and improving aresource utilization rate and a data transmission efficiency.

The method for determining a transmission mode in a sidelink accordingto an implementation of the present disclosure is described above indetail from the perspective of terminal device with reference to FIG. 1to FIG. 3, and a method for determining the transmission mode in thesidelink according to an implementation of the present disclosure willbe described below from the perspective of a network device withreference to FIG. 4.

FIG. 4 shows a schematic flowchart of a method 300 for determining atransmission mode in a sidelink according to an implementation of thepresent disclosure. The method 300 may be performed by a network device.Specifically, for example, the network device may be the network devicein FIG. 1 or FIG. 2. As shown in FIG. 4, the method 300 includesS310-S330. In S310, a first message sent by a first terminal device isreceived, the first message includes first information, wherein thefirst information includes at least one piece of the followinginformation: a transmission mode adopted by the first terminal devicefor performing a sidelink communication, a group identifier of aterminal device group where the first terminal device is located, andgroup head information of the terminal device group, wherein the grouphead information is used for indicating the group head in the terminaldevice group, and the group head is a terminal device with resourcecoordination or allocation function in the terminal device group, inS320, a first transmission mode in multiple transmission modes isdetermined according to the first message; and in S330, firstconfiguration information is sent to the first terminal device, whereinthe first configuration information is used for indicating the firstterminal device to adopt the first transmission mode to perform thesidelink communication with another terminal device.

Optionally, as an implementation, if the first terminal device is not agroup head in the terminal device group, the group head informationfurther includes identification information of the group head in theterminal device group; or, if the first terminal device is the grouphead in the terminal device group, the group head information is usedfor indicating that the first terminal device is the group head in theterminal device group.

Optionally, as an implementation, sending the first configurationinformation to the first terminal device includes: sending the firstconfiguration information to a second terminal device, wherein thesecond terminal device is used for sending the first configurationinformation to the first terminal device, and the second terminal deviceis the group head in the terminal device group.

Optionally, as an implementation, the first message further includessecond information, the second information includes at least one pieceof the following information: identification information of a thirdterminal device, transmission mode adopted by the third terminal devicefor performing the sidelink communication, and first indicationinformation, wherein the third terminal device is a terminal deviceother than the first terminal device in the terminal device group, andthe first indication information is used for indicating a cell of thethird terminal device.

Optionally, as an implementation, the first terminal device is the grouphead in the terminal device group.

Optionally, as an implementation, if the third terminal device islocated outside the cell coverage area, the first indication informationis used for indicating that the third terminal device is located outsidethe cell coverage area, or, if the third terminal device is locatedwithin the cell coverage area, the first indication information includesthe cell identification information of the cell where the third terminaldevice is located; or, if the third terminal device is located outsidethe coverage area of the cell where the first terminal device islocated, the first indication information is used for indicating thatthe third terminal device is located outside the coverage area of thecell where the first terminal device is located and/or the secondindication information includes cell identification information of thecell where the third terminal device is located; or, if the thirdterminal device is located within the coverage area of the cell wherethe first terminal device is located, the first indication informationis used for indicating that the third terminal device is located in thecell where the first terminal device is located.

Optionally, as an implementation, the method 300 further includes:second configuration information is sent to the third terminal device,wherein the second configuration information is used for indicating thethird terminal device to adopt the first transmission mode to performthe sidelink communication.

Optionally, as an implementation, the first message is carried in uplinkcontrol information, MAC CE or RRC signaling.

Optionally, as an implementation, the first configuration informationfurther includes at least one piece of the following information: groupidentification information of the terminal device group where the firstterminal device is located, type information of multicast communicationor broadcast communication, RAT class indication information and QoSattribute information.

Optionally, as an implementation, the first configuration information iscarried in broadcast information, RRC signaling or downlink controlinformation.

Therefore, in the method for determining the transmission mode in thesidelink in an implementation of the present disclosure, the networkdevice may configure the transmission mode adopted by one or moreterminal devices when performing the sidelink, especially for multipleterminal devices in unicast or multicast communication, the networkdevice may configure an appropriate transmission mode according to theactual application, thereby avoiding resource conflicts and improving aresource utilization and a data transmission efficiency.

It should be understood that in various implementations of the presentdisclosure, magnitudes of sequence numbers of the various processes donot imply an order of execution of the various processes, which shouldbe determined by their functions and internal logics, and should notconstitute any limitation on implementation processes of theimplementations of the present disclosure.

In addition, the term “and/or” in this specification describes only anassociation relation for describing associated objects and representsthat three relations may exist. For example, A and/or B may representthe following three cases: only A exists, both A and B exist, and only Bexists. In addition, the symbol “/” in this document generally indicatesthat objects before and after the symbol “/” have an “or” relation.

The method for determining a transmission mode in a sidelink accordingto the implementations of the present disclosure is described in detailabove with reference to FIG. 1 to FIG. 4. A terminal device and anetwork device according to implementations of the present disclosurewill be described below with reference to FIG. 5 to FIG. 9.

As shown in FIG. 5, the terminal device 400 according to animplementation of the present disclosure includes a processing unit 410and a transceiving unit 420. Specifically, the processing unit 410 isconfigured to: determine a first transmission mode in multipletransmission modes; and the transceiving unit 420 is configured to:perform a sidelink communication with another terminal terminal byadopting the first transmission mode.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to receive first configuration information sent by a networkdevice, wherein the first configuration information is used forindicating the first transmission mode; and the processing unit 410 isfurther configured to determine the first transmission mode in themultiple transmission modes according to the first configurationinformation.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to send a first message to the network device, the firstmessage includes first information, wherein the first informationincludes at least one piece of the following information: a transmissionmode adopted by the terminal device for performing the sidelinkcommunication, a group identifier of a terminal device group where theterminal device is located, and group head information of the terminaldevice group, wherein the group head information is used for indicatingthe group head in the terminal device group, wherein the group head is aterminal device having a resource coordination or allocation function inthe terminal device group.

Optionally, as an implementation, if the terminal device is not thegroup head in the terminal device group, the group head informationincludes identification information of the group head in the terminaldevice group; or, if the terminal device is the group head in theterminal device group, the group head information is used for indicatingthat the terminal device is the group head in the terminal device group.

Optionally, as an implementation, the first message also includes secondinformation, wherein the second information includes at least one pieceof the following information: identification information of a secondterminal device, transmission mode adopted by the second terminal devicefor performing the sidelink communication, and first indicationinformation, wherein the second terminal device is a terminal deviceother than the terminal device in the terminal device group, and thefirst indication information is used for indicating cell information orcoverage information corresponding to the second terminal device.

Optionally, as an implementation, if the second terminal device islocated outside the cell coverage area, the first indication informationis used for indicating that the second terminal device is locatedoutside the cell coverage area, or, if the second terminal device islocated within the cell coverage area, the first indication informationincludes the cell identification information of the cell where thesecond terminal device is located; or, if the second terminal device islocated outside the coverage area of the cell where the terminal deviceis located, the first indication information is used for indicating thatthe second terminal device is located outside the coverage area of thecell where the terminal device is located and/or the first indicationinformation includes cell identification information of the cell wherethe second terminal device is located; or, if the second terminal deviceis located within the coverage area of the cell where the terminaldevice is located, the first indication information is used forindicating that the second terminal device is located within the cellwhere the terminal device is located.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to receive the second information sent by the second terminaldevice.

Optionally, as an implementation, the second information is carried in asidelink transmission channel, which is a Physical Sidelink ControlChannel (PSCCH) or a Physical Sidelink Shared Channel (PS SCH).

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to send second configuration information to the secondterminal device, wherein the second configuration information is usedfor indicating the second terminal device to adopt the firsttransmission mode to perform the sidelink communication.

Optionally, as an implementation, the first message is carried in uplinkcontrol information, MAC CE or RRC signaling.

Optionally, as an implementation, the first configuration informationfurther includes at least one piece of the following information: groupidentification information of the terminal device group where theterminal device is located, type information of multicast communicationor broadcast communication, RAT class indication information and QoSattribute information.

Optionally, as an implementation, the first configuration information iscarried in broadcast information, RRC signaling or downlink controlinformation.

Optionally, as an implementation, the processing unit 410 is furtherconfigured to determine the first transmission mode in the multipletransmission modes according to a second message, wherein the secondmessage includes third information, and the third information includesthe transmission mode adopted by the terminal device for performing thesidelink communication and/or a group identifier of the terminal devicegroup.

Optionally, as an implementation, the second message further includesfourth information, wherein the fourth information includes at least onepiece of the following information: identification information of thethird terminal device, transmission mode adopted by the third terminaldevice for performing the sidelink communication, and second indicationinformation; wherein the third terminal device is a terminal deviceexcept the terminal device in the terminal device group, and the secondindication information is used for indicating the cell information orcoverage information corresponding to the third terminal device.

Optionally, as an implementation, if the third terminal device islocated outside the cell coverage area, the second indicationinformation is used for indicating that the third terminal device islocated outside the cell coverage area; or, if the third terminal deviceis located within the cell coverage area, the second indicationinformation includes the cell identification information of the cellwhere the third terminal device is located; or, if the third terminaldevice is located outside the coverage area of the cell where theterminal device is located, the second indication information is usedfor indicating that the third terminal device is located outside thecoverage area of the cell where the terminal device is located and/orthe second indication information includes cell identificationinformation of the cell where the third terminal device is located; or,if the third terminal device is located within the coverage area of thecell where the terminal device is located, the second indicationinformation is used for indicating that the third terminal device islocated in the cell where the terminal device is located.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to receive fourth information sent by the third terminaldevice.

Optionally, as an implementation, the fourth information is carried in asidelink transmission channel, wherein the sidelink transmission channelis PSCCH or PSSCH.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to send third configuration information to the third terminaldevice, wherein the third configuration information is used forindicating the third terminal device to adopt the first transmissionmode to perform the sidelink communication.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to receive fourth configuration information sent by a fourthterminal device, wherein the fourth configuration information is usedfor indicating the first transmission mode; and the processing unit 410is further configured to determine the first transmission mode in themultiple transmission modes according to the fourth configurationinformation.

Optionally, as an implementation, the terminal device is a terminaldevice in the terminal device group except the group head, wherein thegroup head is a terminal device with resource coordination or allocationfunction in the terminal device group, and the fourth terminal device isthe group head in the terminal device group.

Optionally, as an implementation, the transceiving unit 420 is furtherconfigured to send fifth information to the network device or the fourthterminal device, wherein the fifth information includes at least onepiece of the following information: the transmission mode adopted by theterminal device for performing the sidelink communication, the groupidentifier of the terminal device group, and third indicationinformation, wherein the third indication information is used forindicating cell information or coverage information corresponding to theterminal device.

Optionally, as an implementation, if the terminal device is locatedoutside the cell coverage area, the third indication information is usedfor indicating that the terminal device is located outside the cellcoverage area; or, if the terminal device is located within the cellcoverage area, the third indication information includes the cellidentification information of the cell where the terminal device islocated; or, if the terminal device is located outside the coverage areaof the cell where the fourth terminal device is located, the thirdindication information is used for indicating that the terminal deviceis located outside the coverage area of the cell where the fourthterminal device is located and/or the third indication informationincludes cell identification information of the cell where the terminaldevice is located; or, if the terminal device is located within thecoverage area of the cell where the fourth terminal device is located,the third indication information is used for indicating that theterminal device is located within the cell where the fourth terminaldevice is located.

It should be understood that the terminal device 400 according to animplementation of the present disclosure may correspondingly perform themethod 200 in an implementation of the present disclosure, and the aboveoperations and/or functions and other operations and/or functions ofeach unit in the terminal device 400 are respectively for implementingeach corresponding process of the terminal device of any of the methodsin FIG. 1 to FIG. 4, which will not be repeated here for the sake ofbrevity.

Therefore, a terminal device in an implementation of the presentdisclosure may be configured with a transmission mode adopted whenperforming a sidelink through a network device or other terminaldevices, and especially for multiple terminal devices in a unicast ormulticast communication, an appropriate transmission mode may beconfigured according to actual applications, thereby avoiding resourceconflict and improving a resource utilization rate and a datatransmission efficiency.

As shown in FIG. 6, a network device 500 according to an implementationof the present disclosure includes a processing unit 510 and atransceiving unit 520. Specifically, the transceiving unit 520 isconfigured to receive a first message sent by a first terminal device,the first message includes first information, wherein the firstinformation includes at least one piece of the following information: atransmission mode adopted by the first terminal device for performing asidelink communication, a group identifier of the terminal device groupwhere the first terminal device is located, and group head informationof the terminal device group, wherein the group head information is usedfor indicating a group head in the terminal device group, the group headis a terminal device with resource coordination or allocation functionin the terminal device group; and the processing unit 510 is configuredto determine a first transmission mode in multiple transmission modesaccording to the first message; and the transceiving unit 520 isconfigured to send first configuration information to the first terminaldevice, wherein the first configuration information is used forindicating the first terminal device to adopt the first transmissionmode to perform the sidelink communication with another terminal device.

Optionally, as an implementation, if the first terminal device is not agroup head in the terminal device group, the group head informationfurther includes the identification information of the group head in theterminal device group; or, if the first terminal device is the grouphead in the terminal device group, the group head information is usedfor indicating that the first terminal device is the group head in theterminal device group.

Optionally, as an implementation, the transceiving unit 520 is furtherconfigured to send the first configuration information to a secondterminal device, wherein the second terminal device is the group head inthe terminal device group.

Optionally, as an implementation, the first message further includessecond information, and the second information includes at least onepiece of the following information: identification information of athird terminal device, a transmission mode adopted by the third terminaldevice for performing the sidelink communication, and first indicationinformation, wherein the third terminal device is a terminal deviceother than the first terminal device in the terminal device group, andthe first indication information is used for indicating the cell of thethird terminal device.

Optionally, as an implementation, the first terminal device is the grouphead in the terminal device group.

Optionally, as an implementation, if the third terminal device islocated outside the cell coverage area, the first indication informationis used for indicating that the third terminal device is located outsidethe cell coverage area; or, if the third terminal device is locatedwithin the cell coverage area, the first indication information includesthe cell identification information of the cell where the third terminaldevice is located; or, if the third terminal device is located outsidethe coverage area of the cell where the first terminal device islocated, the first indication information is used for indicating thatthe third terminal device is located outside the coverage area of thecell where the first terminal device is located and/or the secondindication information includes cell identification information of thecell where the third terminal device is located; or, if the thirdterminal device is located within the coverage area of the cell wherethe first terminal device is located, the first indication informationis used for indicating that the third terminal device is located in thecell where the first terminal device is located.

Optionally, as an implementation, the transceiving unit 520 is furtherconfigured to send second configuration information to the thirdterminal device, wherein the second configuration information is usedfor indicating the third terminal device to adopt the first transmissionmode to perform the sidelink communication.

Optionally, as an implementation, the first message is carried in uplinkcontrol information, MAC CE or RRC signaling.

Optionally, as an implementation, the first configuration informationfurther includes at least one piece of the following information: thegroup identification information of the terminal device group where thefirst terminal is located, type information of multicast communicationor broadcast communication, RAT class indication information and QoSattribute information.

Optionally, as an implementation, the first configuration information iscarried in broadcast information, RRC signaling or downlink controlinformation.

It should be understood that the network device 500 according to animplementation of the present disclosure may correspondingly perform themethod 300 in an implementation of the present disclosure, and the aboveand other operations and/or functions of each unit in the network device500 are respectively for implementing each corresponding process of anyof the methods in FIG. 1 to FIG. 4, which will not be repeated here forthe sake of brevity.

Therefore, a network device in an implementation of this application mayconfigure a transmission mode adopted when performing a sidelink for oneor more terminal devices, especially for multiple terminal devices in aunicast or multicast communication, the network device may configure anappropriate transmission mode according to the actual applications,thereby avoiding resource conflict and improving a resource utilizationrate and a data transmission efficiency.

FIG.7 is a schematic diagram of a structure of a communication device600 according to an implementation of the present disclosure. Acommunication device 600 shown in FIG. 7 includes a processor 610,wherein the processor 610 may call and run a computer program from amemory to implement the method in an implementation of the presentdisclosure.

Optionally, as shown in FIG. 7, the communication device 600 may furtherinclude a memory 620, wherein the processor 610 may call and run acomputer program from a memory 620 to implement the method in animplementation of the present disclosure.

In the above, the memory 620 may be a separate device independent of theprocessor 610 or may be integrated in the processor 610.

Optionally, as shown in FIG. 7, the communication device 600 may furtherinclude a transceiver 630, and the processor 610 may control thetransceiver 630 to communicate with other devices. Specifically, thetransceiver 630 may send information or data to other devices or receiveinformation or data sent by other devices.

In the above, the transceiver 630 may include a transmitter and areceiver. The transceiver 630 may further include antennas, and thenumber of antennas may be one or more.

Optionally, the communication device 600 may be a network device of animplementation of the present disclosure, and the communication device600 may implement the corresponding processes implemented by the networkdevice in various methods of the implementations of the presentdisclosure, which will not be repeated here for brevity.

Optionally, the communication device 600 may be specifically a mobileterminal/terminal device of an implementation of the present disclosure,and the communication device 600 may implement the correspondingprocesses implemented by the mobile terminal/terminal device in thevarious methods of the implementations of the present disclosure, whichwill not be repeated here for brevity.

FIG. 8 is a schematic diagram of a structure of a chip according to animplementation of the present disclosure. A chip 700 shown in FIG. 8includes a processor 710, wherein the processor 710 may call and run acomputer program from a memory to implement the method in animplementation of the present disclosure.

Optionally, as shown in FIG. 8, the chip 700 may further include amemory 720, wherein the processor 710 may call and run a computerprogram from the memory 720 to implement the method in an implementationof the present disclosure.

In the above, the memory 720 may be a separate device independent of theprocessor 710 or may be integrated in the processor 710.

Optionally, the chip 700 may further include an input interface 730,wherein the processor 710 may control the input interface 730 tocommunicate with other devices or chips. Specifically, the processor 710may acquire information or data sent by other devices or chips.

Optionally, the chip 700 may further include an output interface 740,wherein the processor 710 may control the output interface 740 tocommunicate with other devices or chips. Specifically, the processor 710may output information or data to other devices or chips.

Optionally, the chip may be applied to a network device of animplementation of the present disclosure, and the chip may implement thecorresponding processes implemented by the network device in variousmethods of the implementations of the present disclosure, which will notbe repeated here for brevity.

Optionally, the chip may be applied to a mobile terminal/terminal deviceof an implementation of the present disclosure, and the chip mayimplement the corresponding processes implemented by the mobileterminal/terminal device in the various methods of the implementationsof the present disclosure, which will not be repeated here for brevity.

It should be understood that the chip mentioned in the implementation ofthe present disclosure may be referred to as a system-level chip, asystem chip, a chip system or a system-on-chip, etc.

FIG. 9 is a schematic block diagram of a communication system 800according to an implementation of the present disclosure. As shown inFIG. 9, the communication system 800 may include a terminal device 810and a network device 820.

Herein, the terminal device 810 may be configured to implement thecorresponding functions implemented by the terminal device in theabove-mentioned method, and the network device 820 may be configured toimplement the corresponding functions implemented by the network devicein the above-mentioned method, which will not be repeated here forbrevity.

It should be understood that, the processor in this implementation ofthis application may be an integrated circuit chip having a signalprocessing capability. In an implementation process, the steps of theforegoing method implementations may be implemented by using anintegrated logic circuit of hardware in the processor or instructions ina form of software. The processor may be a general purpose processor, adigital signal processor (Digital Signal Processing, DSP), anapplication specific integrated circuit (Application Specific IntegratedCircuit, ASIC), a field programmable gate array (Field Programmable GateArray, FPGA) or another programmable logic device, a discrete gate or atransistor logic device, or a discrete hardware component. The processormay implement or perform methods, steps and logical block diagramsdisclosed in this implementation of this application. The generalpurpose processor may be a microprocessor, or the processor may be anyconventional processor or the like. The steps of the method disclosedwith reference to this implementation of this application may bedirectly implemented by a hardware decoding processor, or may beimplemented by a combination of hardware and software modules in thedecoding processor. The software modules may be located in a storagemedium commonly used in the art, such as a random access memory, a flashmemory, a read-only memory, a programmable read-only memory or anelectrically erasable programmable memory, or a register. The storagemedium is located in the memory, and the processor reads the informationin the memory and completes the acts of the above method in combinationwith its hardware.

It may be understood that, the memory in this implementation of thisapplication may be a volatile memory or a non-volatile memory, or mayinclude both a volatile memory and a non-volatile memory. Thenon-volatile memory may be a read-only memory (Read-Only Memory, ROM), aprogrammable read-only memory (Programmable ROM, PROM), an erasableprogrammable read-only memory (Erasable PROM, EPROM), an electricallyerasable programmable read-only memory (Electrically EPROM, EEPROM), ora flash memory. The volatile memory may be a random access memory(Random Access Memory, RAM), and is used as an external cache. Throughexemplary but not limitative description, many forms of RAMs may beused, for example, a static random access memory (Static RAM, SRAM), adynamic random access memory (Dynamic RAM, DRAM), a synchronous dynamicrandom access memory (Synchronous DRAM, SDRAM), a double data ratesynchronous dynamic random access memory (Double Data Rate SDRAM, DDRSDRAM), an enhanced synchronous dynamic random access memory (EnhancedSDRAM, ESDRAM), a synchronous link dynamic random access memory(Synchlink DRAM, SLDRAM), and a direct rambus dynamic random accessmemory (Direct Rambus RAM, DR RAM). It should be noted that the memoryin the systems and methods described in this specification is aimed atincluding but being not limited to these and any memory of anotherproper type.

It should be understood that, the foregoing memory is an example forillustration and should not be construed as limiting. For example,optionally, the memory in the implementations of the present disclosuremay be a Static RAM (SRAM), a Dynamic RAM (DRAM), a Synchronous DRAM(SDRAM), a Double Data Rate SDRAM (DDR SDRAM), an Enhanced SDRAM(ESDRAM), a Synchlink DRAM (SLDRAM), a Direct Rambus RAM (DR RAM), orthe like. That is, memories in the implementations of the presentdisclosure are intended to include, but are not limited to, these andany other suitable types of memories.

An implementation of the present disclosure further provides a computerreadable storage medium configured to store a computer program.

Optionally, the computer readable storage medium may be applied to anetwork device of an implementation of the present disclosure, and thecomputer program enables the computer to perform the correspondingprocesses implemented by the network device in various methods of theimplementations of the present disclosure, which will not be repeatedhere for brevity.

Optionally, the computer readable storage medium may be applied to amobile terminal/terminal device of the implementation of the presentdisclosure, and the computer program enables the computer to perform thecorresponding processes implemented by the mobile terminal/terminaldevice in various methods of the implementations of the presentdisclosure, which will not be repeated here for brevity.

An implementation of the present disclosure further provides a computerprogram product including computer program instructions.

Optionally, the computer program product may be applied to a networkdevice of an implementation of the present disclosure, and the computerprogram instructions enable a computer to perform the correspondingprocesses implemented by the network device in various methods of theimplementations of the present disclosure, which will not be repeatedhere for brevity.

Optionally, the computer program product may be applied to a mobileterminal/terminal device of an implementation of the present disclosure,and the computer program instructions enable the computer to perform thecorresponding processes implemented by the mobile terminal/terminaldevice in various methods of the implementations of the presentdisclosure, which will not be repeated here for brevity.

An implementation of the present disclosure further provides a computerprogram.

Optionally, the computer program may be applied to a network device ofan implementation of the present disclosure. When the computer programis run on a computer, the computer is enabled to perform thecorresponding processes implemented by the network device in variousmethods of the implementations of the present disclosure, which will notbe repeated here for brevity.

Optionally, the computer program may be applied to a mobileterminal/terminal device of an implementation of the present disclosure.When the computer program is run on a computer, the computer is enabledto perform the corresponding processes implemented by the mobileterminal/terminal device in various methods of the implementations ofthe present disclosure, which will not be repeated here for brevity.

Those of ordinary skill in the art will recognize that the exemplaryelements and algorithm acts described in combination with theimplementations disclosed herein may be implemented in electronichardware, or a combination of computer software and electronic hardware.Whether these functions are implemented in hardware or software dependson the specific application and design constraints of the technicalsolution. Skilled artisans may use different methods to implement thedescribed functions in respect to each particular application, but suchimplementation should not be considered to be beyond the scope of thepresent disclosure.

Those skilled in the art may clearly understand that for convenience andconciseness of description, the specific working processes of thesystems, apparatuses and units described above may refer to thecorresponding processes in the method implementations and will not bedescribed here.

In several implementations provided by the present disclosure, it shouldbe understood that the disclosed systems, apparatuses and methods may beimplemented in other ways. For example, the apparatus implementationsdescribed above are only illustrative, for example, the division of theunits is only a logical function division, and there may be otherdivision manners in actual implementation, for example, multiple unitsor components may be combined or integrated into another system, or somefeatures may be ignored or not executed. On the other hand, the mutualcoupling or direct coupling or communication connection shown ordiscussed may be indirect coupling or communication connection throughsome interface, apparatus or unit, and may be in electrical, mechanicalor other forms.

The unit described as a separate component may or may not be physicallyseparated, and the component shown as a unit may or may not be aphysical unit, i.e., it may be located in one place or may bedistributed over multiple network units. Some or all of the units may beselected according to actual needs to achieve the purpose of theimplementations.

In addition, various functional units in various implementations of thepresent disclosure may be integrated in one processing unit, or thevarious units may be physically present separately, or two or more unitsmay be integrated in one unit.

The functions may be stored in a computer readable storage medium ifrealized in a form of software functional units and sold or used as aseparate product. Based on this understanding, the technical solution ofthe present disclosure, in essence, or the part contributing to theprior art, or the part of the technical solution, may be embodied in theform of a software product stored in a storage medium, including anumber of instructions for enabling a computer device (which may be apersonal computer, a server, or a network device and the like) toperform all or part of the acts of the method described in variousimplementations of the present disclosure. The foregoing storage mediumincludes: any medium that can store program code, such as a USB flashdrive, a removable hard disk, a read-only memory (Read-Only Memory,ROM), a random access memory (Random Access Memory, RAM), a magneticdisk, or an optical disc.

What are described above are merely exemplary implementations of thepresent disclosure, but the protection scope of the present disclosureis not limited thereto. Any variation or substitution that may be easilyconceived by a person skilled in the art within the technical scopedisclosed by the present disclosure shall be included within theprotection scope of the present disclosure. Therefore, the protectionscope of the present disclosure shall be determined by the protectionscope of the claims.

What is claimed is:
 1. A method for determining a transmission mode of asidelink, comprising: sending, by a first terminal device, a firstmessage to a network device, wherein the first message comprises groupidentifier information of a terminal device group where the firstterminal device is located, or identification information of a secondterminal device, wherein the second terminal device is a terminal devicewhich performs unicast communication with the first terminal device;receiving, by the first terminal device, first configuration informationsent by the network device, wherein the first configuration informationis used for indicating a first transmission mode; determining, by thefirst terminal device, the first transmission mode in a plurality oftransmission modes based on the first configuration information; andadopting, by the first terminal device, the first transmission mode toperform a sidelink communication with another terminal device, whereinthe first configuration information comprises: type information ofunicast communication, multicast communication or broadcastcommunication, Quality of Service (QoS) attribute information, and thegroup identification information of the terminal device group where thefirst terminal is located, wherein the transmission mode comprises: mode1 or mode 2, wherein the mode 1 is that the network device allocatestransmission resources for the first terminal device, and the mode 2 isthat the terminal device selects the transmission resources randomly orby sensing.
 2. The method of claim 1, wherein if the first terminaldevice is not a group head in the terminal device group, group headinformation comprises identification information of the group head inthe terminal device group; or if the first terminal device is the grouphead in the terminal device group, the group head information is usedfor indicating that the first terminal device is the group head in theterminal device group.
 3. The method of claim 1, wherein if the secondterminal device is located outside a cell coverage area, firstindication information is used for indicating that the second terminaldevice is located outside the cell coverage area; or if the secondterminal device is located within the cell coverage area, the firstindication information comprises cell identification information of acell where the second terminal device is located; or if the secondterminal device is located outside a coverage area of a cell where thefirst terminal device is located, the first indication information isused for indicating that the second terminal device is located outsidethe coverage area of the cell where the first terminal device is locatedand/or the first indication information comprises the cellidentification information of the cell where the second terminal deviceis located; or if the second terminal device is located within thecoverage area of the cell where the first terminal device is located,the first indication information is used for indicating that the secondterminal device is located in the cell where the first terminal deviceis located.
 4. The method of claim 3, further comprising: receiving, bythe first terminal device, second information sent by the secondterminal device.
 5. The method of claim 4, wherein the secondinformation is carried in a sidelink transmission channel, and thesidelink transmission channel is a Physical Sidelink Control Channel(PSCCH) or a Physical Sidelink Shared Channel (PSSCH).
 6. The method ofclaim 1, further comprising: sending, by the first terminal device,second configuration information to the second terminal device, whereinthe second configuration information is used for indicating the secondterminal device to adopt the first transmission mode to perform thesidelink communication.
 7. The method of claim 1, wherein the firstmessage is carried in uplink control information, a Media Access ControlControl Element (MAC CE), or a Radio Resource Control (RRC) signaling.8. The method of claim 1, wherein the first configuration informationfurther comprises the identification information of the second terminaldevice which performs unicast communication with the first terminaldevice.
 9. The method of claim 1, wherein the first configurationinformation is carried in broadcast information, or RRC signaling.
 10. Amethod for determining a transmission mode of a sidelink, comprising:receiving a first message sent by a first terminal device, wherein thefirst message comprises group identifier information of a terminaldevice group where the first terminal device is located, oridentification information of a second terminal device, wherein thesecond terminal device is a terminal device which performs unicastcommunication with the first terminal device; determining a firsttransmission mode in a plurality of transmission modes according to thefirst message; and sending first configuration information to the firstterminal device, wherein the first configuration information is used forindicating the first terminal device to adopt the first transmissionmode to perform the sidelink communication with another terminal device,wherein the first configuration information comprises: type informationof unicast communication, multicast communication or broadcastcommunication, Quality of Service (QoS) attribute information, and thegroup identification information of the terminal device group where thefirst terminal is located, wherein the transmission mode comprises: mode1 or mode 2, wherein the mode 1 is that the network device allocatestransmission resources for the first terminal device, and the mode 2 isthat the terminal device selects the transmission resources randomly orby sensing.
 11. The method of claim 10, wherein the first message iscarried in uplink control information, a Media Access Control ControlElement (MAC CE), or a Radio Resource Control (RRC) signaling.
 12. Themethod of claim 10, wherein the first configuration informationcomprises at least one piece of following pieces of information: theidentification information of the second terminal device which performsunicast communication with the first terminal device.
 13. The method ofclaim 10, wherein the first configuration information is carried inbroadcast information, or RRC signaling.
 14. A terminal device,comprising: a processor and a transceiver, wherein the transceiver isconfigured to send a first message to a network device, wherein thefirst message comprises group identifier information of a terminaldevice group where the terminal device is located, or identificationinformation of a second terminal device, wherein the second terminaldevice is a terminal device which performs unicast communication withthe first terminal device, and receive first configuration informationsent by the network device, wherein the first configuration informationis used for indicating a first transmission mode; and the processor isconfigured to determine the first transmission mode in a plurality oftransmission modes based on the first configuration information; whereinthe transceiver is further configured to adopt the first transmissionmode to perform a sidelink communication with another terminal device,wherein the first configuration information comprises: type informationof unicast communication, multicast communication or broadcastcommunication, Quality of Service (QoS) attribute information, and thegroup identification information of the terminal device group where thefirst terminal is located, wherein the transmission mode comprises: mode1 or mode 2, wherein the mode 1 is that the network device allocatestransmission resources for the first terminal device, and the mode 2 isthat the terminal device selects the transmission resources randomly orby sensing.
 15. The terminal device of claim 14, wherein if the terminaldevice is not a group head in the terminal device group, group headinformation comprises identification information of the group head inthe terminal device group; or if the terminal device is the group headin the terminal device group, the group head information is used forindicating that the terminal device is the group head in the terminaldevice group.
 16. The terminal device of claim 14, wherein if the secondterminal device is located outside a cell coverage area, firstindication information is used for indicating that the second terminaldevice is located outside the cell coverage area; or if the secondterminal device is located within the cell coverage area, the firstindication information comprises cell identification information of acell where the second terminal device is located; or if the secondterminal device is located outside a coverage area of a cell where theterminal device is located, the first indication information is used forindicating that the second terminal device is located outside thecoverage area of the cell where the terminal device is located and/orthe first indication information comprises the cell identificationinformation of the cell where the second terminal device is located; orif the second terminal device is located within the coverage area of thecell where the terminal device is located, the first indicationinformation is used for indicating that the second terminal device islocated in the cell where the terminal device is located.
 17. Theterminal device of claim 16, wherein the transceiver is furtherconfigured to: receive second information sent by the second terminaldevice.
 18. The terminal device of claim 17, wherein the secondinformation is carried in a sidelink transmission channel, and thesidelink transmission channel is a Physical Sidelink Control Channel(PSCCH) or a Physical Sidelink Shared Channel (PSSCH).
 19. The terminaldevice of claim 14, wherein the transceiver is further configured to:send second configuration information to the second terminal device,wherein the second configuration information is used for indicating thesecond terminal device to adopt the first transmission mode to performthe sidelink communication.
 20. The terminal device of claim 14, whereinthe first message is carried in uplink control information, a MediaAccess Control Control Element (MAC CE), or a Radio Resource Control(RRC) signaling.
 21. The terminal device of claim 14, wherein the firstconfiguration information further comprises at least one piece offollowing information: the identification information of the secondterminal device which performs unicast communication with the firstterminal device.
 22. The terminal device of claim 14, wherein the firstconfiguration information is carried in broadcast information, or RRCsignaling.
 23. A network device, comprising: a processor and atransceiver, wherein the transceiver is configured to receive a firstmessage sent by a first terminal device, wherein the first messagecomprises group identifier information of a terminal device group wherethe first terminal device is located, or identification information of asecond terminal device, wherein the second terminal device is a terminaldevice which performs unicast communication with the first terminaldevice; and the processor is configured to determine a firsttransmission mode in a plurality of transmission modes according to thefirst message; wherein the transceiver is configured to send firstconfiguration information to the first terminal device, wherein thefirst configuration information is used for indicating the firstterminal device to adopt the first transmission mode to perform asidelink communication with another terminal device, wherein the firstconfiguration information comprises: type information of unicastcommunication, multicast communication or broadcast communication,Quality of Service (QoS) attribute information, and the groupidentification information of the terminal device group where the firstterminal is located, wherein the transmission mode comprises: mode 1 ormode 2, wherein the mode 1 is that the network device allocatestransmission resources for the first terminal device, and the mode 2 isthat the terminal device selects the transmission resources randomly orby sensing.
 24. The network device of claim 23, wherein the firstmessage is carried in uplink control information, a Media Access ControlControl Element (MAC CE), or a Radio Resource Control (RRC) signaling.25. The network device of claim 23, wherein the first configurationinformation further comprises the identification information of thesecond terminal device which performs unicast communication with thefirst terminal device.
 26. The network device of claim 23, wherein thefirst configuration information is carried in broadcast information, orRRC signaling.